Convert 7Z to ZIP
7z compresses better than almost anything else, which is exactly why people send it — and why the recipient often cannot open it. Neither Windows nor macOS reads 7z out of the box. Converting to ZIP trades some size for something that opens everywhere by double-clicking.
Every entry is decompressed with libarchive's 7z reader, which handles LZMA, LZMA2, BZip2 and stored entries, and then re-compressed into a new ZIP container built here in the tab.
The archive is read by code running in this tab. It is not uploaded, not queued on a server, and not seen by anyone but you — which also means there is no size limit imposed from outside, only what your own device can hold.
- Step 1Drop one or more .7z files. The signature is checked, so a mis-named file is still identified correctly.
- Step 2Review the listing: entry count, expanded size, compression ratio and any encrypted or unsafe entries.
- Step 3Convert. Each ZIP is parsed again after it is written and only offered if it reads back correctly.
Drag archives here
.7z— or anything else, and the format will be identified from the file’s own bytes. Files stay on this device.
What this page will not do
Every limit below is a real one, checked against real archives. None of them are upsells — there is no paid tier, and nothing here gets better by signing in.
- Encrypted 7z archives cannot be converted. libarchive reports “The file content is encrypted, but currently not supported” for this build, and where the headers are encrypted too the file list cannot even be read. A password box would be dishonest here, so there is not one for 7z.
- Multi-volume 7z sets (.7z.001, .7z.002 …) are not supported. Rejoin them with 7-Zip first.
- 7z's per-entry timestamps are not exposed by this decoder, so converted files are dated from when the job ran.
- Because 7z usually compresses harder than ZIP, the converted archive is normally larger. That is the format's doing, not a fault in the conversion.
If it did not work
“The archive header is encrypted”
Why: The 7z was created with -mhe=on, which encrypts the file list as well as the contents.
Do this: Nothing here can read it, including the names of the files inside. Decrypt it once with 7-Zip and bring back the plain archive.
Conversion is slower than expected
Why: LZMA decompression is genuinely expensive, and it is running on your device rather than on a server farm.
Do this: It runs off the main thread, so the page stays usable. For a big batch, leave the tab open — progress is per-entry and accurate, not a guess.
“This file is not an archive in any format this site can read”
Why: The bytes do not start with the 7z signature. The file may be a renamed something-else, or truncated.
Do this: Try the archive viewer, which reports whatever the file actually is. If it was downloaded, the download may be incomplete.
Questions
Which 7z compression methods work?
LZMA, LZMA2, BZip2, Deflate and stored entries all decode. Rarer filters can appear in exotic archives; if one is present the affected entry is reported as failed by name rather than being silently skipped.
Will the ZIP be much bigger?
Usually 10–40% bigger, depending on content. 7z's LZMA has a far larger dictionary than ZIP's DEFLATE. Text and source code show the biggest difference; already-compressed media barely changes.
Can I convert several at once?
Yes. Drop as many as you like. The queue runs several at a time on a desktop and one at a time in Safari and on phones, where running two WebAssembly decoders together risks the browser reclaiming the tab.